Bailly, Xhaka, Wijnaldum, others must be wary of second-season syndrome

With Man United and Chelsea back in the Champions League, will this year's competition now be tighter than ever?

First impressions matter but, in Premier League terms, they can also be deceptive. England's top flight has seen many players initially disappoint having moved to a new club, only to then thrive -- see Robert Pires or Didier Drogba, for example.

Likewise, though, there are also those who look sensational initially but prove to be one-season wonders; Michu and Roque Santa Cruz were superb upon their arrival, only to entirely underwhelm after that.

Here are three players approaching their second season at their current club, who are well-placed to push on, as well as three others, who might struggle to live up to their debut campaign.

Eric Bailly (Manchester United)

The Ivorian defender impressed in pretty much every aspect of centre-back play during his debut campaign at Old Trafford; he's physically commanding, assured in possession and reads the game intelligently. There were some positional problems and he dived into tackles rather too readily in the opening months. But, as he gained experience in a solid team under a defensive-minded manager, it was difficult to fault Bailly's game.

He suffered from injuries in the middle of the season and only completed 90 minutes once between Oct. 17 and Feb. 5. When he was fit, he also had to content with being fielded alongside such a variety of teammates. In 19 starts as part of a conventional back four, Bailly partnered with Daley Blind and Chris Smalling seven time apiece, as well as Marcos Rojo four times and Phil Jones once.

If new signing Victor Lindelof is to be his new first-choice partner, Bailly will essentially be the elder statesman, despite being only 23 and just four months older than the Swede. But he has the ability and personality to be a leader and, by the end of next season, might be considered one of the league's best; the same goes for his teammate Paul Pogba.

Granit Xhaka (Arsenal)

The 2016-17 season was a curious one for Xhaka, who arrived to much fanfare last summer as Arsene Wenger's most significant holding midfield purchase in many years. But the opening to his campaign was difficult; first he was omitted from Arsenal's starting XI, then he drew too much attention for careless mistakes, particularly his ability to get into trouble with referees. He was one of only three players sent off twice in the Premier League.

Yet by the end of the campaign -- after he'd served his second ban -- Xhaka was starting every game and was a surprising beneficiary of Wenger's switch to a 3-4-3 formation. In a positional sense his role didn't change too much, but the balance worked nicely between him and Aaron Ramsey, who was given greater licence to get forward. Xhaka, Meanwhile, had the protection of an extra man in defence behind him.

Xhaka's long-range passing came into its own, his tackling was calmer and more precise and he also offered a goalscoring threat from range with his powerful left foot. It feels like he simply needed to learn about the Premier League; his second campaign should see him emerge as one of Arsenal's leaders.

Eric Bailly, left, and Leroy Sane, right, each have what it takes to improve even more next season.

Leroy Sane (Manchester City)

The first thing you notice when watching Sane is simple: his speed. Whereas many modern-day wide players are desperate to come inside and show their invention from between the lines, he is an old-school winger who hugs the touchline and then sprints in behind.

In the first half of last season Sane was usually fielded as a substitute and he started just four times before Christmas, once as a wing-back vs. Chelsea. Injury then kept him out but, when he returned, he became a fixture, starting 16 of the final 17 games as Pep Guardiola played a more consistent XI. Sane scored against Tottenham, Sunderland, Arsenal and Southampton, generally when using his speed in behind the opposing defence.

But it feels like there's more to come; this is a player capable of reaching double figures in goals. A year of experience in England, combined with a greater understanding of Guardiola's methods, should help. Sane might also be able to perform better physically this season, having undergone surgery on a nose problem that left him unable to breathe properly. Perhaps that will, ahem, help him sniff out more goals that turn his potential into efficiency.

David Luiz (Chelsea)

Luiz's huge improvement upon his return to English football seemingly stemmed primarily from Antonio Conte's system. After all, ask any Paris Saint-Germain supporter what happened in Ligue 1 to transform him into a top-class player and they'll likely look at you blankly; he was making plenty of mistakes in France.

In a four-man backline Luiz always appeared somewhat reluctant to defend in a traditional manner, often standing off opponents for too long before recklessly diving into tackles. Now he plays a calmer, more reserved game as the spare man, sweeping up behind two centre-back colleagues. But there's no guarantee that Conte will stick with his three-man defence.

Toward the end of last season, it felt like opposition managers started to work out how to play against Chelsea's 3-4-3, whether by matching the shape -- as Arsenal did in the FA Cup final -- or by exploiting the weaknesses of individual defenders. If Conte does change his approach, Luiz won't look as assured and his position could be under threat.

Idrissa Gueye (Everton)

Gueye was one of Everton's outstanding players last season. Despite a disappointing debut Premier League campaign with Aston Villa, in which he suffered relegation, his impressive ball-winning statistics were enough to get him a move to Goodison Park. Sure enough, he continued where he left off and only N'Golo Kante recorded ball-winning figures as impressive. On tackles alone, Gueye managed 100 to the Chelsea man's 81.

There's a sense, though, that Gueye is a somewhat limited footballer: A pure destroyer, a scrapper who breaks up play rather than starting positive passing moves. Now, with Everton signing a number of exciting, creative players, there will be a change in the approach of Ronald Koeman's side and that could go two ways.

Perhaps Koeman will pack his side with so many attack-minded players that Everton need someone to stay back and mind the defence, a la Claude Makelele at Real Madrid. But it's just as likely that opponents will sit deeper and concentrate on denying space, meaning more guile is needed from deeper positions. Morgan Schneiderlin is a better all-round midfielder and, with Davy Klaassen sure to start and Tom Davies an option for his energy, Gueye might no longer be an automatic first-choice.

Georginio Wijnaldum (Liverpool)

Wijnaldum's impact at Liverpool last season was impressive. He played well on his debut in a win at Arsenal and was a regular in a left-centre midfield role, contributing to Liverpool's consistent pressing approach. He regularly stormed into the box too; his headed winner against Manchester City on New Year's Eve was particularly memorable.

The problem for Wijnaldum, however, is that he doesn't contribute anything unique. He's a fine all-round midfielder and useful in terms of balance but Jurgen Klopp's superior options mean he might well be demoted to the bench. For example, Mohamed Salah has been signed presumably to play in a front three alongside Sadio Mane and Roberto Firmino, meaning Philippe Coutinho is likely to drop back into midfield.

With Adam Lallana one of Liverpool's most impressive performers and Jordan Henderson providing discipline in the holding role, it feels like Wijnaldum -- somewhat unfortunately -- might be the odd man out. Klopp will still need his services as a useful option for rotation and tactical reasons. Whether Wijnaldum will contribute significantly to a title charge, however, is up for question.

Michael Cox is the editor of zonalmarking.net and a contributor to ESPN FC. Follow him on Twitter @Zonal_Marking.